The James Webb Space Telescope (JWST) has significantly reshaped our understanding of the early universe by revealing galaxies that are much more massive than previously predicted. Just weeks after commencing its observations, the JWST discovered a remarkable galaxy, designated Y1, existing approximately 600 million years after the Big Bang. This discovery challenges existing theories of galaxy formation and necessitates further explanation from researchers.
A team at the Atacama Large Millimetre/submillimetre Array (ALMA) has provided insights into Y1, as detailed in the research titled, “A warm ultraluminous infrared galaxy just 600 million years after the Big Bang,” published in the Monthly Notices of the Royal Astronomical Society. The lead author, Tom Bakx, a postdoctoral researcher at Chalmers University of Technology in Sweden, explained that Y1 has a star formation rate (SFR) approximately 180 times that of the Milky Way, producing around 180 solar masses of stars each year compared to the Milky Way’s 1 solar mass.
This elevated SFR suggests that early galaxies, like Y1, could have formed more rapidly and extensively than previously thought. The light reaching us from Y1 is redshifted, indicating that it has traveled for more than 13 billion years. The high luminosity of Y1 implies a larger mass than current models allow for early galaxies.
Understanding Y1’s Unique Features
The research highlights the significance of light in understanding cosmic phenomena. Astronomers observe red light emitted from superheated dust in Y1, which obscures its high SFR. Bakx noted in a press release, “We’re looking back to a time when the universe was making stars much faster than today.” The presence of dust in Y1 made it the furthest galaxy from which direct light has been detected.
To investigate Y1’s characteristics, the team employed ALMA to measure the galaxy’s temperature, with findings indicating that its dust temperature is approximately 90 Kelvin (or -180 degrees Celsius). In comparison, the Milky Way’s dust temperature ranges from 20 to 40 Kelvin. The difference in temperature reflects their respective SFRs, with Y1’s high temperature indicative of its extreme star-forming activity.
Co-researcher Yoichi Tamura, an astronomer at Nagoya University in Japan, emphasized the importance of this finding, stating, “This confirmed that it really is an extreme star factory.” The researchers believe that such star factories could have been common in the early universe, leading to the discovery of massive galaxies earlier than anticipated.
Implications for Galaxy Formation Theories
The implications of this research extend beyond the specific case of Y1. It raises questions about the amount of dust found in early galaxies and how this relates to their age and composition. Traditionally, astronomers associate dust with older stars, particularly evolved red giant stars, which are the primary sources of galactic dust. However, the findings suggest that galaxies like Y1, despite their youth, contain more dust than expected.
Co-author Laura Sommovigo from the Flatiron Institute and Columbia University pointed out that, “Galaxies in the early universe seem to be too young for the amount of dust they contain.” This discrepancy arises because a small amount of warm dust can be as luminous as larger quantities of cooler dust, which is exactly what observations of Y1 reveal.
The study concludes that Y1 serves as an extreme example of dust-obscured star formation, contributing significantly to the cosmic buildup of stellar mass. Bakx noted the necessity for further research, stating, “We want to look for more examples of star factories like this.” The high-resolution capabilities of ALMA will allow researchers to delve deeper into the mechanisms driving star formation in early galaxies.
With these discoveries, the JWST continues to challenge established astrophysical theories and expand our understanding of the universe’s formation and evolution. As researchers explore further, they may uncover more about the nature of galaxies in the early universe and their profound implications for the cosmos.
